Machine for driving mine roof pins

ABSTRACT

A machine for driving mine roof pins having a pin-centering support extending along a cylinder and supported by a piston so as to move with the piston when the piston drives the pin along the cylinder and into a mine roof, the pin-centering support engaging the pin to guide and support the pin after the pin is driven, and moving laterally out of the cylinder as it disengages from that portion of the pin about to enter the mine roof. The pin-centering support includes a plurality of support lengths engaging the side of the pin about the pin periphery, each support length having a plurality of interengaging, relatively movable support members. A secondary power mechanism is operatively connected to the support lengths for urging the support lengths back into the cylinder incident to retraction of the piston. Each support length engages the pin with substantially no relative movement therebetween and moves relative to the cylinder as the pin is driven by the piston means. In one embodiment, the support lengths are spaced substantially equidistantly about the pin periphery, and adjacent support members of each support length have substantially continuous and aligned pin-engaging surfaces to provide a substantially continuous, longitudinal support for the pin. Further, adjacent support members of the support lengths are pivotally interconnected to provide chains. A receiving assembly is provided to guide the support as it moves laterally from the cylinder. An auxiliary support selectively engages the side of the pin about the pin periphery in the region unsupported by the primary pin-centering support near the top of the cylinder and selectively disengages from the side of the pin and out of the path of the piston means to enable complete insertion of the pin by the piston.

United States Patent 1 Elders et al.

[451 May 22, 1973 [54] MACHINE FOR DRIVING MINE ROOF PINS [76] Inventors: Gerald W. Elders, 10 Hillcrest, Christopher, 111. 62822; Thomas E. Schneider, deceased, late of 601 E. Park St., DuQuoin, Ill. 62832 Thomas R. Schneider, administrator; John R. Alongi, 350 E. Main Street, DuQuoin, 111. 62832 [22] Filed: Oct. 6, 1971 [21] Appl. No.: 186,848

Related US. Application Data [63] Continuation-impart of Ser. No. 846,795, Aug. 1,

Primary Examiner-Granville Y. Custer, Jr. Att0rneyCohn, Powell & Hind 5 7 ABSTRACT A machine for driving mine roof pins having a pincentering support extending along a cylinder and supported by a piston so as to move with the piston when the piston drives the pin along the cylinder and into a mine roof, the pin-centering support engaging the pin to guide and support the pin after the pin is driven, and moving laterally out of the cylinder as it disengages from that portion of the pin about to enter the mine roof. The pin-centering support includes a plurality of support lengths engaging the side of the pin about the pin periphery, each support length having a plurality of interengaging, relatively movable support members. A secondary power mechanism is operatively connected to the support lengths for urging the support lengths back into the cylinder incident to retrac tion of the piston. Each support length engages the pin with substantially no relative movement therebetween and moves relative to the cylinder as the pin is driven by the piston means. In one embodiment, the support lengths are spaced substantially equidistantly about the pin periphery, and adjacent support members of each support length have substantially continuous and aligned pin-engaging surfaces to provide a substantially continuous, longitudinal support for the pin. Further, adjacent support members of the support lengths are pivotally interconnected to provide chains. A receiving assembly is provided to guide the support as it moves laterally from the cylinder. An auxiliary support selectively engages the side of the pin about the pin periphery in the region unsupported by the primary pin-centering support near the top of the cylinder and selectively disengages from the side of the pin and out of the path of the piston means to enable complete insertion of the pin by the piston.

18 Claims, 8 Drawing Figures Patented May 22, 1973 3,734,380

5 Sheets-Sheet 2 GERALD W. ELDEIZe THOMAQ E. CHNEWDE2 JOHN CZ. ALONCJ MACHINE FOR DRIVING MINE ROOF PINS CROSS REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of copending application Ser. No. 846,795, filed Aug. 1, 1969.

BACKGROUND OF THE INVENTION This invention relates generally to improvements in roof bolting for mines, and more particularly to an improved machine for setting pins in mine roofs.

In the heretofore conventional method of installing roof bolts in mine roofs, a hole approximately 1 inch in diameter is drilled into the roof which is adapted to receive a inch bolt and expansion shell. The expansion shell is located on the bolt andinserted into the drill hole, the bolt being turned to expand the shell into gripping engagement with the hole wall. The hole is drilled to a depth until a solid roof strata is reached and the expansion shell is anchored in this roof strata. It will be understood that the roof is hung from this bolt. There are essentially two separate operations in installing the bolt, namely, (1) drilling the hole, and (2) installing the bolt and shell in the hole and tightening the bolt under torque. The expansion shell represents the only bearing area holding the bolt in the roof.

In many instances, there are areas in a mine in which there is no sufficiently rigid roof strata in which to anchor an expansion shell. This type of installation is not successful in those areas. Moreover, in many instances, sufficient anchorage strength is not achieved because support is limited by the amount of bearing area presented by the expansion shell. The bolt does not contact the roof material. Tightening the bolt upon application of torque does not increase the holding power because it is limited by the type of material engaging the expansion shell. The drilling of the hole in the mine roof has a tendency to relieve any compressive pressures inherent between the roof strata. Roof jacks are used only when the roof condition represents a hazard to the well-being of the miners and are used to keep the rock from falling. At the present time, the greatest source of injury in a mine is caused by rock falling from the roof. In addition, a further health hazard is created by the drilling of such roof holes, in that the dust is particularly harmful to the lungs and eyes of the miners.

In other fields of endeavor, pins have been driven into walls by hammers that applied a series of abrupt impact shock blows to the pins. This manner of driving pins is undesirable in mines because the impacts tend to disturb the otherwise stable condition of the roof strata, not only in the immediate area in which the pin is driven, but for a considerable distance in all directions, and can adversely affect the holding power of previously driven pins.

The pin-setting device disclosed in the above identified, copending application Ser. No. 846,795, includes an elongate cylinder having an open end and a closed end, and a piston movably mounted in the cylinder. A positioning means locates the open end of the cylinder at the predetermined area of the roof, and means introduces fluid into the cylinder at one side of the piston to move the piston and to press the pin located in the cylinder into the mine roof under a substantially smooth pushing force. The positioning means subjects the mine roof to the compressive pressure in the predetermined area to force the roof strata tightly together so that the pin will hold the strata in such condition. This compressive pressure can be applied by jacks extending between the mine roof and floor.

The pin that was pressed into the mine roof by the device disclosed in the copending application included a plurality of discs carried by and axially spaced along the shank, the discs and pin shank having a frictional connection that enabled slidable axial movement of the discs along the shank until the discs engage the block as the pin was pressed into and through the block and into the mine roof. These discs require time to be placed on the pin shank, and adversely affected the internal wall of the cylinder against which such discs frictionally bear. Moreover, these discs were permanently installed to the mine roof upon complete insertion of the pin, and therefore constituted expendable items that increased costs.

SUMMARY OF THE INVENTION The present machine for driving mine roof pins eliminates the need for drilling any holes in the roof, thereby eliminating any dust hazard that heretofore has been injurious to the miners, and avoiding the relief of roof pressure. Moreover, the need for driving the pin by hammer blows is also eliminated, thereby eliminating the undesirable and potentially dangerous conditions that are caused by such impact shock. The pin is pressed into the mine roof with a substantially smooth pushing force that avoids any chipping or removal or shock disturbance of roof material. The pin periphery contacts the material of the mine roof for greater holding power and is not limited merely by the bearing surface provided by an expansion shell. Because the pin is pushed into the mine roof upon installation, there is no torque applied to the pin. It is not necessary to find 'a limestone roof strata in order to provide an effective installation of the pin when it is placed in position. Moreover, the need for pin discs is eliminated, thereby contributing to greater life of the pin cylinder and avoiding relatively expendable items that increase cost.

The present machine for driving mine roof pins includes a piston means movably received in an elongate cylinder, the piston means providing a seat for the mine roof pin located in the cylinder. A pin-centering support means extends along the cylinder and is supported by the piston means so as to move with the piston means when the piston means drives the pin along and out of the cylinder and into the mine roof, the pincentering support means engaging the pin to guide and support the pin as the pin is driven, and moving laterally out of the cylinder as it disengages from that portion of the pin about to enter the mine roof.

The pin-centering support means includes a plurality of support lengths engaging the side of the pin about the pin periphery, each support length having a plurality of interengaging, relatively movable support members. Each support length has one end portion attached to and movable with the piston means.

With this assembly, each support length engages the pin with substantially no relative movement therebetween and moves relatively to the cylinder wall as the pin is driven by the piston means.

Adjacent support members of each support length have substantially continuous and aligned-engaging surfaces to provide a substantially continuous, longitudinal support for the pin.

A receiving means is provided to guide the support means as it moves laterally from the cylinder. More particularly, the receiving means includes tracks that engage the support lengths as they move laterally outwardly of the cylinder and direct the support lengths into predetermined paths.

A secondary power means is operatively connected to the support lengths for urging the support lengths back into the cylinder incident to retraction of the piston means.

In one embodiment of the invention, the adjacent support members of the support lengths are pivotally interconnected to provide chains. The cylinder includes an open end through which the pin is driven and the support means extends and moves laterally outwardly of the cylinder open end as the pin is driven by the piston means. The support members of each support length engage the pin with substantially no relative movement therebetween and move relative to and against the cylinder as the pin is driven. The receiving means receives each support length as it moves outwardly from the pin cylinder open end. The receiving means includes a cylinder for each support length, and a piston is movably mounted in each support cylinder and is operatively connected to the support length received in the associated receiving cylinder for u ging the support length back into the pin cylinder incident to retraction of the pin-driving piston means. Moreover, the receiving means includes tracks extending substantially from the pin cylinder open end to each of the receiving cylinders, the support lengths engaging the tracks and being directed into the receiving cylinders.

An auxiliary pin support means selectively engages the side of the pin about the pin periphery in the region unsupported by the primary pin-centering support means near the top of the cylinder, and selectively disengages from the side of the pin and out of the path of the piston means to enable complete insertion of the pin by the piston means. The auxiliary pin support means includes a trip mechanism located in the path of the piston means and actuated by the piston means when the pin is nearly fully driven so as to withdraw the auxiliary pin support away from the pin and out of the path of the piston means.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of the pin driving machine;

FIG. 2 is an enlarged top plan view of the pin driving machine, with the top pressure plate partially broken away to more clearly disclose underlying parts;

FIG. 3 is an enlarged, cross sectional view taken along the longitudinal axis of the pin cylinder;

FIG. 4 is a cross sectional view as taken along line 44 of FIG. 3;

FIG. 5 is a side elevational view as taken along line 55 of FIG. 3;

FIG. 6 is a bottom plan view of the auxiliary support means as taken along line 66 of FIG. 3;

FIG. 7 is an elevational view as taken along line 7-7 of FIG. 3; and

FIG. 8 is a cross sectional view as taken along line 8-8 of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT:

Referring now by characters of reference to the drawings and first to FIG. 1, it will be understood that the pin driving machine generally indicated by 10 is located and extends between a mine roof 11 and a subjacent mine floor 12.

The machine 10 includes an elongate pin cylinder 13, and a positioning means provided by a pair of hydraulic jacks referred to by 14 located at opposite sides of the pin cylinder 13. Each hydraulic jack 14 includes an elongate cylinder 15, the jack cylinders 15 and the pin cylinder 13 being secured together by a pair of embracing brackets 16.

As is conventional, and as is disclosed in the copending application Ser. No. 846,795, a piston (not shown) is reciprocatively mounted in each jack cylinder 15 and is attached to an elongate piston rod 17. The piston rod 17 extends through the closed bottom end of each jack cylinder 15 and is connected to a base 18 that seats on the mine floor 12.

The upper end of each hydraulic jack cylinder 15 is closed by a pressure plate 20. When used, the hydraulic jacks 14 are retracted and the machine is disposed in a substantially upright position with the base 18 seating on the mine floor 12. A wood block 21 is disposed on top of the pressure plate 20 overlapping the open cylinder end 22. Upon extension of the hydraulic jacks 14, the pressure plate 20 will urge the wood block 21 against the mine roof l1 and will clamp the block 21 in place at the predetermined roof area.

A plurality (four in the embodiment shown) of receiving cylinders are attached to and supported by the base 18 and extend upwardly along the pin cylinder 13. As is illustrated in FIG. 1, a pair of such receiving cylinders 23 are located at each side of the machine. The structure and function of these receiving cylinders 23 will be explained upon later detailed description of parts.

From FIG. 3, it is seen that a piston 24 is located and slidably mounted in cylinder 13, the piston 24 including a reduced portion 25 that provides an internal socket 26 adapted to seat and hold the head 27 of an elongate pin 28 that is to be driven into the mine roof 11.

The pressure plate 20 is provided with a central opening 30 that is aligned with and located above the open cylinder end 22, the opening 30 being of sufficient diameter to permit passage of the pin head 27 and the piston portion 25 as the pin 28 is completely driven. Mounted to the top of pressure plate 20 by fasteners 31 is a flat ring 32, the ring 32 being concentric with the plate opening 30. The wood block 21 is adapted to seat on this ring 32. A bearing disc 33 is adapted to fit into the space provided by the internal diameter of ring 32 and between the wood block 21 and the top surface of pressure plate 20. This bearing disc 33 engages the pin head 27 when the pin 28 is fully driven and is retained by the pin head 27 against the wood block 21.

A pin-centering support means generally indicated by 34 extends along the cylinder 13 and is supported by the piston 24 so as to move with the piston when the piston drives the pin 28 along and out of the cylinder 13 and into the mine roof 11. The pin-centering support means 34 includes a plurality of support lengths 35 (four in the preferred embodiment) extending into the cylinder 13 between the pin 28 and the internal wall 36 of cylinder 13. Each support length 35 includes a plurality of interengaging, relatively movable support members 37. Each support member 37 includes a pair of laterally spaced, integral ears 38 adapted to embrace a projecting lug 40 of the next adjacent support member 37. A pivot pin 41 extends through the overlapping ears 38 and projecting lug 40 to pivotally interconnect the adjacent support members 37. When so connected, the support length 35 constitutes a chain in which the support members 37 are relatively movable.

When the support members 37 are disposed in vertical alignment within the cylinder 13, the adjacent margins 42 of adjacent support members 37 are in abutment. A bearing surface 43 is provided on the inner margin of each support member 37, the bearing surface 43 being arcuate and conforming substantially to the periphery of the pin shank. The opposite and outermost margin of each support member 37 is provided with a foot pad providing an arcuate bearing surface 44 conforming substantially to the arcuate configuration of the inner cylinder wall 36. It will be understood that when the support members 37 of each support length 35 are aligned within the cylinder 13, the bearing surfaces 43 are in substantial alignment and form a substantially continuous bearing support against the shank of pin 28. The bearing surfaces 43 engage the pin shank while the bearing surfaces 44 engage the cylinder wall 36. Accordingly, the support lengths 35 center and support the pin 28 to preclude any undesirable deformation or buckling of the pin shank as the pin 28 is pushed under tremendous pressure into the mine roof.

The end of each support length 35 includes a plurality of end support members 45 that do not engage the pin 28 but rather serve to connect the support length to the piston 24. For example, each end support member 45 includes a pair of laterally spaced, integral ears 46 embracing a body portion of the adjacent end support member 45. A pivot pin 47 extends through the overlapping ears and body portion to pivotally interconnect the adjacent end support members 45. These end support members 45 include inner bearing surfaces 48 adapted to engage the reduced piston portion 50,

and outer bearing surfaces 51 on integral foot pads adapted to engage the cylinder wall 36. One of the end support members is pivotally connected to an adjustable threaded element 52 fixed to the top surface of piston 24, while another end support member 45 is pivotally connected to the first of the support members 37 engageable with the pin shank.

In the preferred embodiment four support lengths 35 are provided, equidistantly spaced around the pin periphery, for the most efficient centering and support of the pin shank.

A receiving means generally indicated by 53 directs each of the support lengths 35 in a predetermined path as the support length 35 moves laterally out of the cylinder 13. The receiving means includes the cylinder 23 that has an open end 55 into which each support length 35 moves. A pair of laterally spaced plates 56 are secured to the underside of the pressure plate 20, and are provided with internal tracks 57 extending from the open end 22 of pin cylinder 13 to the open end 55 of the associated receiving cylinder 23. Mounted on opposite ends of each pivot pin 41 are rotatable bearings 58 that ride in and on the internal plate tracks 57. In order for the support members 37 of each support length 35 to provide maximum support for the pin shank, the underside of the pressure plate 20 is provided with an arcuate groove 60 into which the support members 37 move as each support length 35 moves laterally out of the pin cylinder 13.

A secondary power means is provided for urging the support lengths 35 back into the pin cylinder 13 incident to retraction of the piston 24. This secondary power means includes a piston 61 reciprocatively mounted within each receiving cylinder 23. A link 62 pivotally interconnects the last support member 37 to an adjustable threaded member 63 fixed to the top surface of piston 61. When the pressure is removed from the underside of piston 24, after the pin 28 is driven, fluid pressure is exerted on the underside of each piston 61, thereby moving the piston 61 upwardly within the receiving cylinder 23, moving the support length 35 back into the pin cylinder 13, and retracting the piston 24.

It will be understood that as the support members 37 of each support length 35 move laterally out of the pin cylinder 13, such support members 37 will disengage from the pin shank at a slight distance below the pressure plate 20 and thereby expose a short length of pin shank that is unsupported by the support lengths 35. While this exposed length of pin shank is very small and is rarely, if ever, buckled or deformed during driving of the pin 28, an auxiliary support means indicated by 64 is provided as a safety precaution to preclude such possibility. This auxiliary support means 64 consists of two units arranged at diametrically opposite sides of the pin shank. A detailed description of one unit will suffice for the other.

Each unit of the auxiliary support means 64 includes a pair of longitudinal, laterally spaced body plates 65 and 66, end plates 67 and 68, and interconnecting top wall 70 fixed to the under surface of pressure plate 20. Attached to the top wall 70 and located between the spaced body plates 65 and 66 is a catch block 71. Also located between the spaced plates 65 and 66 is a support body 72 having an end wall 73 fixed to a plunger rod 74. A compression spring 75 is located about the plunger rod 74, and is located between the end plate 67 and rod head 76, the spring 75 tending to urge the plunder rod 74 outwardly. The inner end of the support body 72 is provided with an arcuate bearing surface 77 adapted to engage the periphery of the shank of pin 28 in the region below the pressure plate 20 that is unsupported by the pin-centering and support means 34. This end of support body 72 is provided with side ribs 78 slidably received within compatible grooves 80 formed in the end plate 68 to guide the body 72 in its reciprocative motion.

The support body 72 includes a pair of depending, integral lugs 81 and 82 that are laterally spaced to receive a lever 83 therebetween. A pivot pin 84 pivotally attaches the lever 83 to the lugs 81 and 82. A pair of laterally spaced links 85 and 86 are attached to opposite sides of one end of lever 83 by a pivot pin 87. The opposite ends of links 85 and 86 are pivotally connected by pin 88 to a latch body 90 that is located in a hollow chamber of the support body 72. The latch body 90 is pivotally connected to opposite sides of the support body 72 by a pivot pin 91. When the support body 72 is moved to its pin-supporting position shown in FIG. 3, the latch body 90 engages the catch block 71 to hold the support body 72 in such position against the loading of spring 75. Another spring 92 has one end en- 7 gaging the lever 83 in alignment with the pivot pin 84 and an opposite end engaging the latch member 90, the spring 92 tending to urge the latch body 90 upwardly into latch engagement with the catch block 71.

The upper end of pin cylinder 13 is provided with a lateral slot 93 to permit movement of the supporting unit toward and away from the pin 28.

It is thought that the operation and functional advantages of the pin-driving machine have become fullyapparent from the foregoing detailed description of parts, but for completeness of disclosure, the operation will be briefly described. It will be assumed that a pin 28 has been completely driven so that the auxiliary support means 64 has been retracted away from the pin, that the support lengths 35 of the pin-centering support means 34 have moved laterally out of the pin cylinder 13 and into the receiving cylinders 23, and that the piston 24 is in its uppermost position.

The hydraulic jacks 14 are retracted so as to lower the pressure plate away from the mine roof 11 sufficiently to enable the machine to be tilted for insertion of another roof pin 28. The roof pin 28 is inserted through the plate opening 30 and into the pin cylinder 13 so that the pin head 27 is received in the socket 26. The pressure on the underside of the piston 24 is relieved, and hydraulic pressure is exerted on the underside of the pistons 61 of the auxiliary power means. As the pistons 61 are moved upwardly in their receiving cylinders 23, the support lengths are moved outwardly of such cylinders 23 and into the pin cylinder 13, thereby retracting the piston 24. As the support members 37 of the support lengths 35 move into the pin cylinder 13, the bearing surfaces 43 engage the pin shank and the bearing surfaces 44 engage the cylinder wall 36. It will be understood that the pin 28 is centered by the support lengths 35 and is held in position as the piston 24 moves to its lowermost position in the pin cylinder 13. When the piston 24 is located in its fully retracted position, fluid pressure is relieved from the underside of the pistons 61 in the receiving cylinders 23.

The auxiliary support means 64 is then moved to its operative position to support the pin shank. For example, the plunger rod 74 of each unit is depressed under the loading of spring 75 until the latch body 90 clears the catch block 71, at which time the latch member 90 will move upwardly under the loading of spring 92 to engage the catch block 71 and lock the support body 72 in place. In such position, the bearing surface 77 of each support body 72 engages or is closely located to the periphery of the pin shank.

Then a wood block 21 is located on top of the pressure plate 20 overlying the bearing disc 33 and the pin 28.

The machine is moved to a substantially upright position with the pressure plate 20 and the wood block 21 located below the region of the mine roof in which the roof pin 28 is to be driven. The hydraulic jacks 14 are then actuated to move the wood block 21 up against the mine roof and to exert a compressive force on the mine roof through the pressure plate 20.

Fluid pressure is then exerted in the pin cylinder 13 below the piston 24, moving the piston 24 upwardly so that the pin 28 moves through the wood block 21 and penetrates the strata of the mine roof 11. As the pin 28 moves upwardly and is driven under this substantially smooth pushing force into the mine roof 11, the pin is supported at all times by the pin-centering support means 34. More particularly, the support members 37 of each support length 35 move upwardly with the piston 24 so that the bearing surfaces 43 engage the pin periphery with relatively no movement therebetween, while the bearing surfaces 44 slide on the cylinder wall 36. This longitudinal support provided by the support lengths 35 about the periphery of the pin 28 preclude any buckling or deformation of the pin shank as the pin 28 is driven into the mine roof 11 under the high pressure exerted by piston 24.

As the pin 28 is driven, the support members 37 of each support length 35 will move laterally outwardly of the pin cylinder 13 in the region just below the pressure plate 20. In fact, these support lengths 35 move outwardly of the open end 22 of the pin cylinder 13, but it will be understood that lateral ports could be provided in the pin cylinder 13 for this purpose. As each support member 37 of each support length 35 approaches the exit from pin cylinder 13, the roller bearings 58 engage the internal tracks 57 of guide plates 56, and the support lengths 35 are then moved in an arcuate path out of the pin cylinder 13 and into the open end 55 of the receiving cylinders 23.

When the pin 28 is nearly fully driven, the last of the support members 37 of the support links 35 is moved away from the pin shank so that the pin shank is then solely supported laterally by the auxiliary support means 64. As the piston 24 moves upwardly for a further distance, the forwardmost, reduced piston portion 25 will clear the innermost ends of levers 83 until such piston portion 25 closely approaches the support body 72 which is in its path. At this time, the levers 83 of the auxiliary support means engage the ledge 54 provided between the reduced piston portions 25 and 50, causing the latch bodies to trip out of effective engagement with the catch blocks 71 and thereby releasing the support bodies 72 for movement away from the pin 28 and out of the path of the piston 24 under the loading of springs 75. Upon continued upward movement of the piston 24, the pin 28 is fully driven with the pin head 27 engaging the bearing disc 33 and the underside of the wood block 21. The cycle is then repeated for subsequent driving of pins.

We claim as our invention:

1. In a machine for driving mine roof pins:

a. an elongate cylinder,

b. a mine roof pin located in the cylinder,

c. piston means movably received in the cylinder, the piston means providing a seat for the mine roof pin, and

d. a pin-centering support means extending along the cylinder and moving with the piston means when the piston means drives the pin along and out of the cylinder and into a mine roof, the pin-centering support means engaging the pin to guide and support the pin as the pin is driven, and moving laterally out of the cylinder as it disengages from that portion of the pin about to enter the mine roof.

2. A machine for driving mine roof pins as defined in claim 1, in which:

e. the pin-centering support means includes a plurality of support lengths engaging the side of the pin about the pin periphery, each support length including a plurality of interengaging, relatively movable support members.

3. A machine for driving mine roof pins as defined in claim 2, in which:

f. each support length has one end portion attached to and movable with the piston means.

4. A machine for driving mine roof pins as defined in claim 2, in which:

f. each support length engages the pin with substantially no relative movement therebetween and moves relative to the cylinder as the pin is driven by the piston means.

5. A machine for driving mine roof pins as defined in claim 2, in which:

f. the support lengths are spaced substantially equidistantly about the pin periphery.

6. A machine for driving mine roof pins as defined in claim 2, in which:

f. adjacent support members of each support length have substantially continuous and aligned pinengaging bearing surfaces to provide a substantially continuous, longitudinal support for the pin.

7. A machine for driving/mine roof pins as defined in claim 1, in which:

e. receiving means guide the pin-centering support means as it moves laterally from the cylinder.

8. A machine for driving mine roof pins as defined in claim 2, in which:

f. receiving means include tracks that engage the support lengths as they move laterally outwardly from the cylinder and direct the support lengths into predetermined paths.

9. A machine for driving mine roof pins as defined in claim 2, in which:

f. a secondary power means is operatively connected to the support lengths for urging the support lengths back into the cylinder incident to retraction of the piston means.

10. A machine for driving mine roof pins as defined in claim 2, in which:

f. the adjacent support members of the support lengths are pivotally interconnected to provide chains.

11. A machine for driving mine roof pins as defined in claim 10, in which:

.g. each support member has a first bearing surface engageable with the pin and a second bearing surface slidably engageable with the wall of the cylinder.

12. A machine for driving mine roof pins as defined in claim 10, in which:

g. the cylinder includes an open end through which the pin is driven,

h. the pin-centering support means extends and moves laterally outwardly of the cylinder open end as the pin is driven by the piston means,

. the support members engage the pin with substantially no relative movement therebetween and move relative to and against the wall of the cylinder as the pin is driven by the piston means, and j. receiving means receive each support length as it moves outwardly from the pin cylinder open end, and direct the support length into a predetermined path. 7

13. A machine for driving mine roof pins as defined in claim 12, in which:

k, the receiving means includes a receiving cylinder for each support length, and

l. a piston movably mounted in each receiving cylinder and operatively connected to the support length received in said receiving cylinder for urging the support length back into the pin cylinder incident to retraction of the pin-driving piston means.

14. A machine for driving mine roof pins as defined in claim 13, in which:

m. the receiving means includes tracks extending substantially from the pin cylinder open end to the receiving cylinders, the support lengths engaging the tracks and being directed into the receiving cylinders as the support lengths move outwardly from the pin cylinder open end.

15. A machine for driving mine roof pins as defined in claim 1, in which:

e. the pin cylinder includes an open end through which the pin is driven,

f. a pressure plate is located adjacent to the open end of the pin cylinder, the pressure plate being provided with an opening aligned with the pin cylinder open end, and the pressure plate being provided with a plurality of substantially curvilinear grooves in one side communicating with the pin cylinder open end and spaced about the pin periphery,

g. the support means includes a plurality of support lengths engaging the side of the pin about the pin periphery and aligned with the plate grooves, each support length engaging the pin with substantially no relative movement therebetween and movably engaging the cylinder as the pin is driven by the piston means,

' h. each support length contains a plurality of pivotally connected support members disposed in longitudinal alignment when disposed in the cylinder be tween the pin and the cylinder, adjacent support members being provided with substantially longitudinally aligned bearing surfaces engageable with the pin along its length, the aligned pin-engaging surfaces of the adjacent support members being substantially contiguous to provide a substantially continuous, longitudinal support for the pin,

. receiving means includes:

1. a receiving cylinder for and receiving each support length as it moves laterally outwardly from the pin cylinder, and

2. tracks extending substantially from the pin cylinder to the receiving cylinders,

j. bearings are provided at the pivotal connections between adjacent support members, the bearings engaging the tracks to direct the support members into and along the pressure plate grooves as the support members move outwardly from the pin cylinder and thence into the receiving cylinders.

16. A machine for driving mine roof pins as defined in claim 1, in which:

e. an auxiliary support means selectively engages the side of the pin about the pin periphery in the region unsupported by the pin-centering support means near the top of the cylinder, and selectively disengage from the side of the pin and out of the path of the piston means to enable complete insertion of the pin by the piston means.

17. A machine for driving mine roof pins as defined in claim 16, in which:

f. the auxiliary support means includes a trip mechanism in the path of the piston means and actuated by the piston means when the pin is nearly fully driven so as to withdraw the auxiliary support means away from the pin and out of the path of the piston means.

18. A machine for driving mine roof pins as defined in claim 17, in which:

g. the auxiliary support means includes a springloaded plunger having a bearing surface engaging the side of the pin, and

h. the trip mechanism selectively holds the plunger 

1. In a machine for driving mine roof pins: a. an elongate cylinder, b. a mine roof pin located in the cylinder, c. piston means movably received in the cylinder, the piston means providing a seat for the mine roof pin, and d. a pin-centering support means extending along the cylinder and moving with the piston means when the piston means drives the pin along and out of the cylinder and into a mine roof, the pin-centering support means engaging the pin to guide and support the pin as the pin is driven, and moving laterally out of the cylinder as it disengages from that portion of the pin about to enter the mine roof.
 2. A machine for driving mine roof pins as defined in claim 1, in which: e. the pin-centering support means includes a plurality of support lengths engaging the side of the pin about the pin periphery, each support length including a plurality of interengaging, relatively movable support members.
 2. tracks extending substantially from the pin cylinder to the receiving cylinders, j. bearings are provided at the pivotal connections between adjacent support members, the bearings engaging the tracks to direct the support members into and along the pressure plate grooves as the support members move outwardly from the pin cylinder and thence into the receiving cylinders.
 3. A machine for driving mine roof pins as defined in claim 2, in which: f. each support length has one end portion attached to and movable with the piston means.
 4. A machine for driving mine roof pins as defined in claim 2, in which: f. each support length engages the pin with substantially no relative movement therebetween and moves relative to the cylinder as the pin is driven by the piston means.
 5. A machine for driving mine roof pins as defined in claim 2, in which: f. the support lengths are spaced substantially equidistantly about the pin periphery.
 6. A machine for driving mine roof pins as defined in claim 2, in which: f. adjacent support members of each support length have substantially continuous and aligned pin-engaging bearing surfaces to provide a substantially continuous, longitudinal support for the pin.
 7. A machine for driving mine roof pins as defined in claim 1, in which: e. receiving means guide the pin-centering support means as it moves laterally from the cylinder.
 8. A machine for driving mine roof pins as defined in claim 2, in which: f. receiving means include tracks that engage the support lengths as they move laterally outwardly from the cylinder and direct the support lengths into predetermined paths.
 9. A machine for driving mine roof pins as defined in claim 2, in which: f. a secondary power means is operatively connected to the support lengths for urging the support lengths back into the cylinder incident to retraction of the piston means.
 10. A machine for driving mine roof pins as defined in claim 2, in which: f. the adjacent support members of the support lengths are pivotally interconnected to provide chains.
 11. A machine for driving mine roof pins as defined in claim 10, in which: g. each support member has a first bearing surface engageable with the pin and a second bearing surface slidably engageable with the wall of the cylinder.
 12. A machine for driving mine roof pins as defined in claim 10, in which: g. the cylinder includes an open end through which the pin is driven, h. the pin-centering support means extends and moves laterally outwardly of the cylinder open end as the pin is driven by the piston means, i. the support members engage the pin with substantially no relative movement therebetween and move relative to and against the wall of the cylinder as the pin is driven by the piston means, and j. receiving means rEceive each support length as it moves outwardly from the pin cylinder open end, and direct the support length into a predetermined path.
 13. A machine for driving mine roof pins as defined in claim 12, in which: k. the receiving means includes a receiving cylinder for each support length, and l. a piston movably mounted in each receiving cylinder and operatively connected to the support length received in said receiving cylinder for urging the support length back into the pin cylinder incident to retraction of the pin-driving piston means.
 14. A machine for driving mine roof pins as defined in claim 13, in which: m. the receiving means includes tracks extending substantially from the pin cylinder open end to the receiving cylinders, the support lengths engaging the tracks and being directed into the receiving cylinders as the support lengths move outwardly from the pin cylinder open end.
 15. A machine for driving mine roof pins as defined in claim 1, in which: e. the pin cylinder includes an open end through which the pin is driven, f. a pressure plate is located adjacent to the open end of the pin cylinder, the pressure plate being provided with an opening aligned with the pin cylinder open end, and the pressure plate being provided with a plurality of substantially curvilinear grooves in one side communicating with the pin cylinder open end and spaced about the pin periphery, g. the support means includes a plurality of support lengths engaging the side of the pin about the pin periphery and aligned with the plate grooves, each support length engaging the pin with substantially no relative movement therebetween and movably engaging the cylinder as the pin is driven by the piston means, h. each support length contains a plurality of pivotally connected support members disposed in longitudinal alignment when disposed in the cylinder between the pin and the cylinder, adjacent support members being provided with substantially longitudinally aligned bearing surfaces engageable with the pin along its length, the aligned pin-engaging surfaces of the adjacent support members being substantially contiguous to provide a substantially continuous, longitudinal support for the pin, i. receiving means includes:
 16. A machine for driving mine roof pins as defined in claim 1, in which: e. an auxiliary support means selectively engages the side of the pin about the pin periphery in the region unsupported by the pin-centering support means near the top of the cylinder, and selectively disengage from the side of the pin and out of the path of the piston means to enable complete insertion of the pin by the piston means.
 17. A machine for driving mine roof pins as defined in claim 16, in which: f. the auxiliary support means includes a trip mechanism in the path of the piston means and actuated by the piston means when the pin is nearly fully driven so as to withdraw the auxiliary support means away from the pin and out of the path of the piston means.
 18. A machine for driving mine roof pins as defined in claim 17, in which: g. the auxiliary support means includes a spring-loaded plunger having a bearing surface engaging the side of the pin, and h. the trip mechanism selectively holds the plunger bearing surface in position against the pin side, and selectively releases the plunger when actuated by the piston means to enable withdrawal under the spring loading. 